Plant bug No. 1 pest in cotton

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The dynamics of cotton pests continue to change from a weevil/worm management system to the bug complexes, according to a report by Mississippi State University Extension entomologist Mike Williams.

According to Cotton Insect Loss Estimates — 2009, which was presented by Williams at the 2010 Beltwide Cotton Conferences in New Orleans, overall losses to insects in 2009, at 2.56 percent, were down from 3.8 percent in 2008. Alabama reported the highest percent loss to insects at 9.38 percent, followed by Oklahoma, 7.76 percent, Missouri, 6.11 percent and Mississippi, 5.94 percent. All other states reported less than 5 percent losses. The annual report is based on a survey of state Extension entomologists across the Cotton Belt.

The total of loss and cost of control to insects in 2009 amounted to $491 million, according to the report. The largest loss plus cost occurred in Texas, $104 million, where the majority of U.S. acreage was planted in 2009.

The costs of insect management were $43.79 per acre in 2009, while cost plus loss were $62.68 per acre.

For the second year in a row Lygus, or plant bug, was the most damaging pest of U.S. cotton, infesting 53 percent of all acreage and causing an average 0.6 percent reduction in yield, or 122,500 bales.

The average cost of control for Lygus, which includes the western and eastern species, was reported at $2.81 per acre. The Mid-South took the biggest hit from plant bugs in 2009. Missouri, 3.71 percent, Arkansas, 2.79 percent, Mississippi, 2.49 percent, Louisiana, 2.14 percent and Tennessee, 1.2 percent, along with Arizona, 1.59 percent, all reported greater than 1 percent loss to Lygus.

The second most damaging pest in 2009, early-season thrips, infested 94 percent of U.S. acreage. Oklahoma, 5 percent, reported the highest losses to thrips, followed by Kansas, 2 percent, and Missouri, 1.28 percent. All other states reported less than 1 percent. North Carolina and New Mexico reported no losses from early-season thrips.

Heliothines were the third most damaging pest in 2009, with cotton bollworm the dominant species at 79 percent. Heliothine damage resulted in the loss of 91,437 bales of cotton, and the pests infested 54 percent of the U.S. crop. Alabama reported the highest loss, 3.4 percent, followed by Georgia, 1.8 percent and Louisiana, 1.06 percent.

Bt cotton acreage dropped by almost 500,000 acres in 2009, due to an overall decrease in cotton acreage. Heliothines were sprayed on 1.075 million Bt cotton acres in 2009. The cost of Bt is estimated at $16.25 per acre for the U.S. crop. This represents about 37 percent of the cost of arthropod management and is the highest cost in arthropod management for 2009.

Silverleaf whitefly was the tenth most damaging pest in 2009, with infestations reported in Arizona, California, Texas, Alabama, Florida, Georgia, Mississippi and South Carolina.

The boll weevil infested only 112,258 acres of cotton in 2009, with only Texas and Louisiana reporting infested acres. That’s quite a drop from the 2.221 million acres the pest infested in 2002. Boll weevils took only 379 bales of cotton in 2009, all in Texas. Eradication costs for boll weevil amounted to $4.34 per U.S. acre.

Losses from all other pests remained almost negligible, according to the survey. Other pests included pale-sided flea beetle, green mirid, beet armyworm, cutworm, looper, bandedwinged whitefly, cotton leaf perforator, grasshopper, saltmarsh caterpillar and southern armyworm.

Pink bollworm infested 81,317 acres of U.S. cotton in 2009. California, Texas and Arizona had infested acres, but no losses. Pink bollworm eradication cost U.S. producers about 26 cents per acre in 2009.

Williams noted that the total losses from insects below 5 percent, “continue to reflect the outstanding contribution technology has made to managing pest complexes which long have plagued cotton producers.”